1. Field of the Invention
This invention relates to an instrument for cutting tissue and, more particularly, to an instrument for creating a hole or flap in the lens capsule of the eye.
2. Description of Related Art
Many surgical procedures require incision of membranes and the like for insertion of instruments. For example, when incising the lens capsule, straight cuts are typically made with cutting instruments having extremely sharp blades and instruments are thereafter inserted to carry out the desired surgical procedure. However, stress concentration occurs at edges of the straight cut when instruments are manipulated in the incision, which may result in tearing of the incision. To eliminate the problems of stress concentration, circular cuts have been proposed. However, the physical nature of tissue being cut often precludes a clean incision, since the tissue may collapse or distort when initial penetration is made with the cutting instrument. Thus, conventional instruments do not facilitate a clean cut since the tissue cannot be properly held during the cutting operation. Further, precise circular cuts cannot be made with conventional instruments due to their slow cutting speeds.
In other surgical procedures, clean cuts are also required to retrieve biopsy specimens or to remove a precise segment of tissue for transplants. For example, in keratoplasty utilizing corneal transplantation, a precise piece of the cornea must be removed.